The present invention relates to an identification system which employs an activator that transmits an identification code which is processed by a controller. The controller may be designed to perform specific functions when a valid identification code has been received. In particular, the identification system is adapted for use in an electronic key system.
Various systems have been developed to replace the use of mechanical keys in order to provide convenience and increase security. One type of electronic key system utilizes an electronic combination pad. Typically, the electronic combination pad consists of a panel of approximately five buttons located in the vicinity of a door knob. The user must depress the buttons in a predefined sequence to disengage the lock. This type of keyless system prove less than desirable because the combination can be forgotten. Furthermore, an unauthorized person can easily obtain the combination by merely observing the user depressing the appropriate code.
Other systems comprise a battery powered electronic device such as an activator. The activator, designed to operate at radio frequencies, sends a preprogrammed code to a control module. Upon verification of an authorized code, the module disengages the lock. These systems have apparent disadvantages. For example, interference from radio communication devices or electrical storms may cause the system to malfunction. In addition, the use of a battery as a portable power source limits the miniaturization of the activators, even when employing current fabrication techniques. It also renders the activator to be bulky and inconvenient to carry around. Moreover, the battery source must be periodically replaced, further inconveniencing the user.
Some systems, such as those disclosed in U.S. Pat. No. 4,453,161, have proposed the use of "a short wave energy field" as a technique for generating a source of power in the activator. Electromagnetic induction, as disclosed in U.S. Pat. No. 4,857,913, has also been proposed as a substitute for using a battery as a power source. However, all of these systems require capacitors associated with the conversion of alternating current (AC) from electromagnetic fields or high frequency energy fields into direct current (DC), which is mandatory to operate the electronic devices. The capacitors, when compared to the other components, are relatively large. As such, the size of the activators may be limited by the size of the capacitors.
From the above, it is apparent that there is a need to provide a passive activator without requiring the use of either a portable power source or capacitors to convert AC to DC. In this manner, the activator could be miniaturized to a size which is amenable to being encased in, for example, a finger ring band. The ring band would be difficult to lose and very convenient to use. The user need not remember difficult combinations nor is there a potential threat of it being stolen by an unnoticed observer.